import 'dart:io';
import 'dart:convert';
import 'dart:mirrors';

getTypeName(dynamic data) {
    return reflect(data).type.reflectedType.toString();
}

void main() {
    var a = '123456';
    var b = base64Encode(utf8.encode(a));
    var aa = String.fromCharCodes(base64Decode(b));
    print(b);
    print(aa);
    print(getTypeName(b));/*String*/
    print(getTypeName(aa));/*String*/
}